The Essential Guide to Vitamin B Vitamins, Vitamin D, and Vitamin C

The B vitamins, vitamin D and vitamin C each do a different job. The eight B vitamins turn food into energy, vitamin D supports your bones and immune system, and vitamin C is an antioxidant your body needs to make collagen. You can get all three from food, but vitamin D and B12 in particular are common gaps, so it's worth checking whether your diet or supplement covers them.

What the B vitamins do

The B vitamins are a group of eight chemically distinct, water-soluble compounds that work together, known as the B-complex. Apart from B12, your body doesn't store much of them, so you need a regular supply from food or supplements.

They're needed to break down carbohydrates, fats and proteins. Without enough, your body struggles to make adenosine triphosphate (ATP), the main energy molecule in your cells, which can show up as ongoing fatigue, brain fog and lower stamina. Our article on the science of B vitamins for energy goes into more detail.

Vitamin B12 (cobalamin) is one of the most important. In a 2009 review in the American Journal of Clinical Nutrition, Allen et al. reported that B12 deficiency affects about 6% of adults under 60 and nearly 20% of those over 60. Vegans and vegetarians are at far higher risk because B12 comes mainly from animal foods. Deficiency can cause nerve problems and megaloblastic anemia.

How vitamin D supports your body

Vitamin D is unusual because your skin makes it when exposed to ultraviolet B (UVB) light. You need it to absorb calcium and build bone, and it's also linked with heart health, mood and immune defense.

Deficiency is common. Forrest and Stuhldreher (Nutrition Research, 2011) found that about 41.6% of US adults are vitamin D deficient, meaning blood levels below 20 ng/mL. That makes it one of the most common deficiencies in developed countries. Where you live, your skin pigmentation and how much time you spend indoors all play a part.

Vitamin D receptors are found on nearly all immune cells, including T cells and B cells. Aranow et al. (Journal of Investigative Medicine, 2011) linked deficiency with more infections and some autoimmune conditions, so adequate vitamin D matters for a steady immune response.

What causes vitamin D deficiency

Sunlight is the main source, so people in northern latitudes and those who always use sun protection may not make enough. Skin also gets less efficient at making vitamin D with age, which raises the risk for older adults.

Food sources are limited: fatty fish such as salmon and mackerel, egg yolks and fortified foods. Many people need a supplement to keep their levels up, especially in winter or if they spend little time outdoors.

Signs of deficiency can include bone pain, muscle weakness and frequent illness, but they're often subtle, so many people don't know until they have a blood test. Healthcare providers usually order a serum 25-hydroxyvitamin D test. See our guide to the signs of vitamin D deficiency.

Why vitamin C matters

Vitamin C (L-ascorbic acid) is probably the best-known antioxidant. Unlike most mammals, humans can't make it, so it has to come from the diet. It neutralizes free radicals, which protects cells and DNA from oxidative damage.

It's also a cofactor for making collagen, the most abundant protein in the body, which gives structure to skin, joints, tendons and blood vessels. Without enough vitamin C, collagen production suffers, connective tissue weakens and wounds heal more slowly.

Vitamin C supports both the innate and adaptive immune systems. It builds up in phagocytic cells such as neutrophils and can improve their ability to move toward and engulf germs. It works best when you keep your levels steady rather than taking it only when you feel ill. For more, see our article on supporting immune function with vitamins.

Common gaps in women

Hormonal changes, reproductive health needs and busy schedules can make it harder for women to meet their needs. Data suggests many women fall short on B vitamins, vitamin D and certain minerals. Our guide to common nutrient gaps in women is a good starting point.

Folic acid (vitamin B9) is needed for cell division and is especially important during the childbearing years. Vitamin C also helps you absorb non-heme iron from plant foods, a reminder that these nutrients work as a network rather than one at a time.

The form matters too. Methylcobalamin is a naturally occurring form of B12 that some people prefer to synthetic cyanocobalamin. Choosing well-absorbed forms helps your body use what you take.

Multivitamin or single supplements?

If your schedule is busy, a multivitamin is a simple way to cover the B vitamins, vitamin D and vitamin C every day without managing several bottles. Our women's multivitamin guide explains what to look for: third-party testing for purity, no unnecessary fillers, and a format you'll actually take. Absorption matters most, because a supplement only helps if your body can use it. Supplements should add to a varied, whole-food diet, not replace it.

Where Go Wise Multivitamin fits

Go Wise Multivitamin is a powder stick you pour onto your tongue, with no water needed and a natural berry flavor. Each stick has vitamins A, C, D3, E, B6 and B12, niacin, pantothenic acid, biotin, folic acid, zinc and chromium, plus elderberry extract and kelp as a natural source of iodine. It's vegan, gluten-free and has no artificial colors or flavors. It doesn't include thiamin (B1) or riboflavin (B2); our B-12 Complex does. Every batch is third-party tested by Eurofins for heavy metals and microbial contamination, and it is made in a GMP-certified facility.

Frequently asked questions

What are the main benefits of B vitamins?

B vitamins are coenzymes that help your body turn food into energy (ATP). They also support your nervous system, brain function, red blood cell formation and DNA synthesis.

How do I know if I have a vitamin D deficiency?

Common signs include ongoing fatigue, bone or joint pain, muscle weakness and more frequent infections. Many people have no symptoms, though, so a blood test for 25-hydroxyvitamin D is the only definitive way to know.

Can I take vitamin D and vitamin C together?

Yes. There are no known negative interactions between them, and they support different parts of immune function and cell health.

What are the best vitamins for vitamin D absorption?

Vitamin D is fat-soluble, so it's absorbed best with a meal that contains healthy fats. Vitamin K2 and magnesium are often recommended alongside it because they help your body use calcium properly in bone.

Why is vitamin C important for skin?

Vitamin C is a cofactor for the enzymes that stabilize and cross-link collagen. It also gives antioxidant protection against UV-related oxidative stress, which helps maintain skin elasticity and appearance.

Is it better to take a multivitamin or individual supplements?

A multivitamin is a convenient way to support general health and fill common gaps. Individual supplements are usually for when a doctor has found a specific, significant deficiency (like a severe vitamin D deficiency) that needs a higher treatment dose.

References

• Allen et al. American Journal of Clinical Nutrition. 2009.
• Forrest and Stuhldreher. Nutrition Research. 2011.
• Aranow et al. Journal of Investigative Medicine. 2011.

This article is for general information and isn't medical advice. Talk to your healthcare provider before starting a supplement, especially if you are pregnant, nursing or taking other medication.